expand

This method takes the first token and expands it. The result is placed
on the stack.
This means that expandable code does one step of expansion and puts the
result on the stack. To expand a token it might be necessary to consume
further tokens.

convertCount

This method converts a register into a count.
It might be necessary to read further tokens to determine which value to
use. For instance an additional register number might be required. In
this case the additional arguments Context and TokenSource can be used.

convertDimen

This method converts a register into a dimen.
It might be necessary to read further tokens to determine which value to
use. For instance an additional register number might be required. In
this case the additional arguments Context and TokenSource can be used.
The return value is the length in scaled points.